What mechanisms contribute to the strength loss that occurs during and in the recovery from skeletal muscle injury?

In the workplace or on the athletic field, muscle strength can be decreased by 50% or more following performance of a relatively few high-force, eccentric contractions. The strength loss can be prolonged, taking a month or more for complete recovery. It is important to understand the cause(s) of the strength loss so we can develop means of preventing or attenuating this loss. The cellular-level mechanisms explaining the loss of strength following contraction-induced muscle injury remain controversial. The traditional thought is that initial strength loss is due solely to damage to force-bearing structures within the muscle, as evidenced by histopathology. In addition, inflammation in the days following injury is commonly thought to exacerbate the strength loss. We present data to the contrary. Recent data show that most of the early strength loss results from a failure of excitation-contraction coupling processes and that a slow loss of contractile protein in the days following injury prolongs the time for recovery.